* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
.container {
  width: 100%;
  margin: 0 auto;
  height: 100px;
  background-color: skyblue;
  max-width: 100%;
  padding: 20px;
}
.container .middle {
  width: 1200px;
  height: 100%;
  background-color: red;
  margin: 0 auto;
  max-width: 100%;
}
